306 



DESCRIPTIVE MrNERALOGY. 



Fig. 248. 



Fis. 249. 



Fis. 247, 



St. Lawrence County. Hornblende, in almost all its varieties, occurs in several parts 



of this county. Crystals of va 

 rious shades of green are found 

 in the vicinity of the village of 

 Gouverneur, where they are 

 often associated with apatite, 

 pyroxene, tourmaline, feldspar 

 and quartz. These crystals are 

 sometimes two or three inches 

 in diameter, but are usually 

 short. The forms observed here 

 are similar to those represented in Fig. 244 ; also Figs. 247, 248 and 249. 



Fine crystals have also been obtained in the town of Dekalb. They often have a diameter 

 of two or three inches, but the prisms arc short. A very perfect one, in the possession of 

 Dr. Emmons, had the form of Fig. 230. Crystals similar to 234, but with the prisms very 

 short, have also been found in this county. 



In the town of Rossie, about two miles north of the village of O.xbow, there is a rock on 

 Fig. 250. the road-side, from which beautiful and perfect crystals of the variety 



pargasite have been obtained. They are of a fine green colour, translu 

 cent, and have a high lustre. The associates are pyroxene, feldspar, 

 sphene and apatite. The usual form is the si.x-sided prism with two 

 terminal planes (Fig. 243) ; often there are found compound crystals, as 

 represented in Fig. 250. This is one of the most interesting localities in 

 the county. 



Resplendent hornblende, in large crystals, associated with other mine- 

 rals, has been found near the bridge at the village of Potsdam ; and a 

 white variety, in crystals terminated at each end, sometimes an inch long 

 by three-eighths of an inch in diameter, has been found near Russel.* 

 On the banks of Yellow lake, in the same town, tremoHte of a blui.sh white colour, and 

 resembling tabular spar, occurs in tiie white limestone ; and the same variety has been found 

 in Gouverneur, and also at Richville and Dekalb, where it is associated with soft pyroxene, 

 brown tourmaline, etc. At ihe latter locality, it is white and grey, fibrous and bladed. 



Tremolite has also been obtained in other parts of the county, and is indeed one of the 

 most common and abundant minerals of the white limestone formation. The asbestus variety 

 occurs in thin veins in the serpentine near the village of Gouverneur, and also near Little 

 York. In the town of Dekalb, it is found in gneiss, and in perpendicular fibres of from a 

 quarter to three quarters of an inch, passing through magnetic iron ore. The latter resembles 

 the byssolite. With this exception, the asbestus heretofore obtained in this county does not 

 possess much interest. 



* Finch. American Journal of Science. XIX. 220. 



